This proposal has dual aims of research training and research in coding of olfactory quality. We have picked this topic because of a common interest in chemosensory coding. The long term research goal is to understand the organization of the olfactory system which gives rise to functional activation and finally the recognition of odors. This project specifically aims to determine the relationship between chemical structure and function within specific zones of the epithelium and the glomeruli. The observation that axons from receptor cells expressing the same receptor gene converge onto the same small number of glomeruli is the source of the following hypotheses to be tested: 1) stimuli which evoke responses in the specific epithelial zones should also evoke responses in similar glomerular regions; 2) there should be greater variance in the order of efficacy in glomerular or glomerular level recordings than in epithelial recordings; 3) the dynamic range of concentration responsiveness should be smaller in the glomeruli than in the epithelium; 4) compounds that tend to activate the same glomeruli or glomerular regions should cross-adapt in the periphery; 5) glomeruli in the same small region of the bulb should respond to most of the same odors. These experiments offer the possibility of developing insights into the relationship between chemical structure and smell, a sensory modality that is important in appetite, social behavior, and endocrine function.